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Abstract
Background
Keratins are structural, thiol-rich proteins, which comprise 90% of total poultry feather weight. Their favourable amino acid profile suggests the potential for use as a protein source and ergogenic aid for endurance athletes, following treatment to increase digestibility. This study investigated whether 4 weeks of soluble keratin (KER) consumption (0.8 g/kg bodyweight/day) by 15 endurance-trained males would have favourable effects on body composition, blood and cardiorespiratory variables, and cycling performance, compared to casein protein (CAS).
Methods
Supplementation was randomized, blinded and balanced, with a minimum eight-week washout period between trials. An exercise test to measure oxygen consumption during submaximal and maximal cycling exercise was completed at the start at and end of each intervention. Anthropometric (DEXA) and blood measures were made prior to and following each intervention period.
Results
Total body mass and percentage body fat did not change significantly (p > 0.05). However, a significantly greater increase in bone-free lean mass (LM) occurred with KER compared to CAS (0.88 kg vs 0.07 kg; p < 0.05). While no change in LM was evident for the trunk and arms, leg LM increased (0.45 ± 0.54 kg; p = 0.006) from baseline with KER. KER was not associated with changes in blood parameters, oxygen consumption, or exercise performance (p > 0.05).
Conclusions
These data suggest that KER is not useful as an ergogenic aid for endurance athletes but may be a suitable protein supplement for maximizing increases in lean body mass.
Acknowledgements
The authors would like to thank the cyclists from the local cycling and triathlon communities who took part in the study and the Massey Institute of Food Science and Technology, who performed the blood and DEXA analyses.
Funding
This study was funded by a Massey University Doctoral Research Dissemination Grant. The consumables required for this study were part-funded by Keraplast Research LTD. The funders had no influence on study design, implementation, data analysis, and interpretation, nor did they contribute to investigator income.
Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.
Authors’ contributions
SS, EC and YM designed the study. EC and YM conducted the study. SS, EC, YM and MB analysed the data. SS, MB and EC wrote the paper. SS had primary responsibility for the final content. All authors read and approved the final content.
Ethics approval and consent to participate
Written and verbal consent were obtained by all participants prior to commencement of the study. This study was approved by the University Human Ethics Committee, in accordance with the Declaration of Helsinki.
Consent for publication
Not applicable.
Competing interests
Keraplast Research (LTD) manufactured and supplied the Kerapro supplements for the research and also contributed to the cost of the DEXA measurements. EC was supported by a Massey University Doctoral Scholarship and YM, a Callaghan Innovation Doctoral Scholarship. The remaining authors received no payment or financial support from Keraplast Research or other external agency.
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